The present invention relates to a method for the production of an aluminum foil for electrolytic capacitors by anodic etching in a bath containing an electrolyte and a counterelectrode with a direct current superimposed by current pulses, or a pulsating direct current, in which the voltage pulses are preferably of such polarity and size that they momentarily and periodically interrupt the etching, followed by subsequent activation.
A method of this type is known from DE-OS No. 15 64 486 and corresponding U.S. Pat. No. 3,520,788. This prior etching method obtains satisfactory results in static etching baths. If, however, continuous etching is conducted, surprisingly the etching attack is non-uniform because of the dynamic effect of the continous bath. The natural surface of the aluminum foil is obviously more or less resistant to the etching attack, and the etching conditions are poorly defined in the immersion area of the bath, especially as a result of the foam produces by the etching.